In recent years,cancer immunotherapy has developed rapidly due to its significant advantages compared with the traditional cancer treatment methods.Tumor immunotherapy aims at mobilizing or stimulating the body's own immune function,thereby inhibiting and killing cancer cells.With the development of nanotechnology,biological nano-carrier materials provide a new insight into the vaccine development.Nano-vaccines are therapeutic or prophylactic vaccines based on nanotechnology including exogenous antigens for inducing immune responses,vectors delivering antigens,and adjuvants for enhancing immunogenicity and accelerating and prolonging the availability of cancer vaccines.Nano-delivery vectors have good biocompatibility as well as unique physical and chemical properties.They can effectively deliver the antigens,and further activated the immune response of antigenspecific cellulars based on the activation of the body's humoral immunity by regulating the presentation pathways in the antigen-presenting cells.In this paper,the applications of nano-delivery systems in cancer vaccine research were summarized.

Objective To study the antigen-specific immune response induced by the graphene oxide (GO) in mice.Methods OVA-loaded GO nano-immunocomplexes (GO-OVA) were prepared by co-incubation of nano GO with model antigen ovalbumin (OVA).Nano GO was characterized by atomic force microscopy and laser particle sizeanalyzer.The cytotoxicity of GO to mouse bone marrow dendritic cells (BMDCs) was detected by cell counting kit (CCK-8).The GO-OVA uptake of BMDCs were observed by fluorescent staining.C57BL/6 mice were divided into OVA group,aluminum adjuvant OVA (Al-OVA) group and GO-OVA group (6 mice in each group) by body weight for in vivo immunization.The levels of OVA-specific antibody IgG (total IgG,IgG1,and IgG2a) in serum of mice were detected by enzyme-linked immunosorbent assay (ELISA).The T lymphocyte subsets in spleen and inguinal lymph nodes of mice were detected by flow cytometry.Results The average particle size of the prepared nano GO was (294.34±4.68) nm,and the polydispersity coefficient was 0.208.Nano GO has less toxicity to mouse BMDCs.The results of in vitro experiments indicated that GO-OVA nanovaccine can be efficiently internalized by mouse BMDCs.The antigen-specific IgG antibodies induced by the GO-OVA was similar to that of aluminum adjuvant and the difference was not statistically significant (P＞0.05),and the Th1-type response was predominant.The proportions of CD4+ and CD8+ T lymphocytes in the spleen and inguinal lymph nodes in GO-OVA group were significantly higher than those in OVA and Al-OVA groups,and the differences were statistically significant (all P＜0.05).Conclusions GO-OVA nano-immunocomplexes can induce both humoral and cellular immune responses in mice,which provides basis for the development of novel vaccine vectors and adjuvants.

Objective To study the maturation and activation effects of hyaluronic acid (HA) modified polymer nanoparticles co-delivering adjuvants and antigens on mouse bone marrow dendritic cells (BMDCs). Methods HA-modified polylactic acid-glycolic acid copolymer (PLGA) and cationic lipid DOTAP were used as nanocarriers (DOTAP-PLGA) to co-deliver adjuvant CpG with model antigen ovalbumin (OVA). In the drug-loaded nanocarriers, CpG was covalently bound to the surface of HA, and OVA was physically blended into DOTAP-PLGA nanocarriers. The nanoparticles were characterized by transmission electron microscopy and dynamic light scattering. The in vitro release of CpG and OVA in the nanoparticles was investigated. The uptake and distribution of nanoparticles in mouse BMDCs were studied by flow cytometry and laser scanning confocal microscopy. The maturation and cytokine expression of mouse BMDCs were evaluated by flow cytometry and enzyme-linked immunosorbent assay, respectively. Results The CpG-HA-OVA-PLGA nanoparticles loading CpG and OVA were prepared. The average particle size was (305.1±2.2) nm and the polydispersity index was 0.203. A core-shell structure of the nanoparticles modified by HA was clearly observed by transmission electron microscopy. Cellular experiment results showed that CpG-HA-OVA-PLGA nanoparticles could be efficiently uptaken by mouse BMDCs, and promote lysosomal release of CpG and cytoplasmic delivery of antigen OVA. Compared with free OVA group and free OVA+CpG group, the CpG-HA-OVA-PLGA nanoparticles significantly up-regulated the expression of co-stimulatory molecules CD86 and CD40 (all P<0.01), major histocompatibility complex I (MHC-I) (P<0.01), and cytokine tumor necrosis factor-α (TNF-α) (P<0.01). Conclusions HA-modified CpG and OVA nanoparticle co-delivery vectors can effectively promote the maturation and activation of dendritic cells, which provides a basis for the development of novel vaccine vectors for the co-delivery of antigens and adjuvants.